The present invention relates to a cleaning apparatus and method that utilize ultrasonic waves and, more particularly, to an ultrasonic cleaning method and apparatus suitable for removing contaminants attaching to the surface of a semiconductor substrate or the like and for drying the semiconductor substrate after the contaminants are removed.
Conventionally, as a method of mechanically removing substances attaching to the surface of an object to be cleaned, e.g., a semiconductor substrate or a reticle, scrub cleaning and ultrasonic cleaning are known.
According to scrub cleaning, a scrub member on which a nylon brush or the like is arranged is rotated. The surface of the cleaning target is cleaned by scrubbing, thereby removing substances attaching to the surface of the cleaning target. According to ultrasonic cleaning, the cleaning target is dipped in a cleaning liquid, which is vibrated within the ultrasonic band to apply vibrations to substances attaching to the surface of the cleaning target, thereby removing the substances.
In scrub cleaning, in order to prevent the scrub member and the cleaning target from coming into direct contact with each other, the cleaning liquid is constantly supplied to the surface of the cleaning target such that it exists between the scrub member and the cleaning target. Sometimes, however, the cleaning liquid does not sufficiently reach the interface between the cleaning target and scrub member, and the cleaning target substrate and the scrub member come into direct contact with each other.
In this case, the cleaning target may break, or the nylon brush or the like of the scrub member wears to generate dust, causing contamination. If a soft scrub member is used in order to prevent wear of the scrub member, the effect of removing the attaching substances may be decreased.
In ultrasonic cleaning, as described above, the substances attaching to the surface of the cleaning target are removed by applying vibrations to them. Hence, it is very difficult to remove film-like attaching substances.
With either cleaning method, recontamination by removed substances attaching to the cleaned target again must be prevented. For this purpose, the cleaning target must be cleaned again before drying. A simple apparatus for achieving this is sought for.